New York's main oil contract, light sweet crude for August delivery, was 22 cents higher at 138.96 dollars a barrel.
The contract sank 6.44 dollars to close at 138.74 dollars a barrel on Tuesday at the New York Mercantile Exchange. It was the sharpest single-session decline since January 1991.
"I was stunned," said Dave Ernsberger, Asia director of global energy information provider Platts. "At one point crude futures fell by 10 dollars in one hour.
Brent North Sea crude for August delivery was 33 cents higher at 139.08 dollars a barrel following a plunge of 5.
17 dollars to settle at 138.75 dollars Tuesday in London.
Analysts said the falls coincided with US Federal Reserve chairman Ben Bernanke's semiannual forecast to Congress, in which he said there was a "high degree of uncertainty" about the US economic outlook.
"The move down started when Ben Bernanke started speaking on television," Ernsberger said.
"It fell while he was talking."
Bernanke said the Federal Rese